Hemo-dialysis is a widely used method of kidney dialysis for treatment of end stage renal disease. In the hemodialysis process a patient's blood is cleansed by passing it through an artificial kidney dialysis machine. This process requires that the patient be physically connected to the machine several times a week so that patient's blood may be transferred to and from the membranes in the machine.
Peritoneal dialysis has been found to be usable with many patients as a more convenient and in many ways desirable alternative to traditional hemo-dialysis. In the peritoneal dialysis process a dialysis solution is infused into the patient's peritoneal cavity using tubing and a catheter. After a given period of time the dialysis solution is removed and replaced.
A peritoneal dialysis apparatus has been disclosed in U.S. patent application Ser. No. 448,450 entitled "Peritoneal Dialysis Apparatus", filed Dec. 10, 1982 and assigned to the assignee of the present application. Such an apparatus discloses therein, and in particular with respect to FIG. 4 thereof, a heater-scale structure usable to continuously heat and to weigh dialysis fluid to be infused into a patient. A similar scale is shown mechanically in FIG. 1 of U.S. patent application Ser. No. 548,390 entitled "Peritoneal Dialysis Apparatus", filed Nov. 3, 1983 also assigned to the assignee of the present application.
A significant problem in peritoneal dialysis heater-scales has been found to lie in the fact that dialysis fluids come in various sizes of bags. Any heater-scale must be usable, with little or no operator intervention, to properly heat bags of different sizes. Additionally, the heater-scale must compensate for the fact that, during a typical dialysis process, the bag will be respectively partially emptied and refilled with fluid of varying temperatures resulting in varying volumes of fluid being heated from different initial temperatures.